Advice needed with using DF54 with Vst (20g) basket on Flair 58

As title says, I am looking for some inputs here. I was able to dial in perfectly using flair's stock basket (low flow) with Df54 on settings between 12-16 (medium roast, 0 is perfectly set). Then I upgraded to vst 20g for better results and shots started flowing pretty faster as expected with straight walled basket. I have reduced the grind settings till 9 but it's still going little fast (20.5g in, 40 out in 28sec). I can reduce dose further or settings lower but wanted to check if anyone has tried with this combination and getting perfect output. Taste wise I can already feel the difference but want to fine tune the recipe. Thanks.